This invention relates to microwave heating ovens having means for preventing the leakage of microwave energy through a gap between the oven body and the oven door during operation of the heating oven, and is more particularly directed to a microwave heating oven wherein the leakage of microwave energy through the gap is prevented by the insertion of a microwave absorber in the gap.
Microwave heating ovens are utilized for heating articles with microwave energy generated by a microwave generating device, in order to raise the temperature of the article within a comparatively short time. The frequency of the microwaves used in the present invention is in a high frequency range, such as 2.45 GHz, as is generally known to those skilled in the art.
In the use of this type of oven, microwave energy leaks through a gap, if present, between the body of the microwave heating oven and the door thereof. Such leakage of microwaves generates noise in radio receivers or TV sets, and additionally may cause radio-frequency burns on the human body.
One of the inventors of the present invention, Ishino, has proposed means for preventing the leakage of microwave energy from a microwave heating oven, as disclosed in U.S. Pat. Nos. 3,742,176 and 3,866,009. In the means as stated above, magnetic material is used as one of the seals, i.e. an absorber of the leaking microwave energy, wherein the magnetic material is a mixture of ferrite powder and an organic high molecular weight compound. The ferrite has the formula: EQU MFe.sub.2 O.sub.4
wherein M is a divalent metal such as Ni, Cu, Zn, Mn, or Mg, and the organic high molecular weight compound is selected from the group consisting of natural rubber and synthetic rubber.